Selective separation of heterogeneous particles



United States Patent 3,298,617 SELECTIVE SEPARATION OF HETERO GENEOUS PARTICLES Edward G. Engel, Westfield, Ben W. Rowland, Hillside, and Andrew Torok, Parsippany, N.J., assignors to Georgia Kaolin Company, a corporation of New Jersey No Drawing. Filed Feb. 14, 1964, Ser. No. 344,822

2 Claims. (Cl. 241-20) This invention relates to selective separation of heterogeneous particles and particularly to the selective separation of particles of differing degrees of hydrophobicity. It is well known that many mineral ores such as the metal sulfides are readily wet by oils and take on a distinct hydrophobic quality whereas the gangue rock with which they are natively associated remains substantially unwet by such oils and retain a distinct hydrophilic quality. It is this significant difference in quality of hydrophobicity which is utilized in well-known flotation techniques for the separation of mineral ores from gangue rock. Such flotation techniques are universally used for separation of ores, particularly metal sulfides from gangue rock and while quite satisfactory for a general or gross separation, they are not satisfactory for making an ultimate purification of such mineral ores. For example molybdenum sulfide is generally separated from its associated gangue rock by flotation techniques to produce a resultant molybdenum sulfide of about 90 to 93% purity. The remaining gangue rock is extremely difficult and expensive to separate from the ore and has posed a very real problem to the art.

We have discovered a process by which the gangue rock can be removed to produce a miner-a1 ore fraction of about 99% purity. We shall describe the invention hereafter as applied to molybdenum sulfide-gangue rock mixtures although it may be similarly applied to other metal ores.

Preferably, we admix a moist, finely divided mineral ore-gangue rock mixture in water in the presence of flotation reagents including a hydrophobic liquid such as a flotation oil. This fluid mixture is then ground to reduce the particle size of the gangue and disperse the hydrophilic gangue phase in the water. The particles of metal sulphide agglomerate during grinding while the gangue rock disperses. The resulting mineral sulphide agglomerates are separated from the water dispersion of comminuted gangue rock by any conventional well known method such as decantation.

The following examples will illustrate the method of our invention and will more clearly explain the details of its operation.

Example I An undried mixture of molybdenum sulfide and gangue rock concentrate resulting from a previous commercial flotation operation and carrying with it the attached flotation oils was placed in a water vehicle. The mixture contained about 92% molybdenum sulfide and the particle size range of gangue rock was in the range of 50 to 100 microns. This mixture was placed in a sand grinder such as described in Field Patent 3,075,710 with 3959.6 grams of 20-30 mesh Ottawa sand; 3436 grams of molybice denum sulfide-gangue mixture and 4157.7 grams of water. The grinder was started. Within five minutes the molybdenum sulfide began agglomerating into small spheres and the gangue rock, which was ground to smaller size, was dispersing in the water phase. This same result was observed at 10, 15, 20 and 30 minute intervals. The mixture was removed and separated. The molybdenum sulfide was agglomerated in spheres of about 1 millimeter diameter and 99% purity whereas the gangue rock had been ground to about 6 to 8 microns in size and remained dispersed in the water phase.

Example II A mixture of molybdenum sulfide-gangue rock identical with that of Example I was made up to 35% solids in water and placed in the sand grinder described in Example I. Results similar to those in Example I were obtained. At the end of 25 minutes the molybdenum had agglomerated into generally spherical particles of about millimeter diameter and the gangue rock was dispersed in the water phase at a size consisting of about 6 to 8 microns.

While we have illustrated and described certain preferred practices of our invention in the foregoing description it will be apparent that this invention may be otherwise embodied within the scope of the following claims.

We claim:

1. The method of separating finely divided heterogeneous particles of two different levels of hydrophobicity comprising the steps of making a flotation separation of the particles to provide a particle system rich in the more hydrophobic member of said heterogenous mixture and carrying a surface coating of flotation agents, mixing the resultant particles in water in the presence of the flotation agents carried thereon, grinding the mixture in a sand grinder to reduce the particle size of the solids and simultaneously agglomerate the particles of greater hydrophobicity while dispersing the particles of lesser hydrophobicity and separating the agglomerates from the resultant dispersion.

2. A method as claimed in claim 1 wherein the finely divided particles originally fed into the flotation system were in the range 50 to 100 microns in size.

References Cited by the Examiner UNITED STATES PATENTS 1,421,862 7/1922 Trent 209166 X 1,509,266 9/1924 Spearman 209166 1,667,277 4/1928 Wilkinson 209-5 X 1,797,356 3/1931 Martin 209-49 1,968,008 7/1934 Chapman 209-49 2,383,045 8/1945 Den Breejen 241l4 X 2,846,151 8/1958 Wehn 241-14 FOREIGN PATENTS 934,796 8/ 1963 Great Britain.

WILLIAM W. DYER, JR., Primary Examiner.

ROBERT C. RIORDON, H. F. PEPPER, Examiners. 

1. THE METHOD OF SEPARATING FINELY DIVIDED HETEROGENEOUS PARTICLES OF TWO DIFFERENT LEVELS OF HYDROPHOBICITY COMPRISING THE STEPS OF MAKING A FLOTATION SEPARATION OF THE PARTICLES TO PROVIDE A PARTICLE SYSTEM RICH IN GHE MORE HYDROPHOBIC MEMBER OF SAID HETEROGENOUS MIXTURE AND CARRYING A SURFACE COATING OF FLOATION AGENTS, MIXING THE RESULTANT PARTICLES IN WATER IN THE PRESENCE OF THE FLOTATION AGENTS CARRIED THEREON, GRINDING THE MIXTURE IN A SAND GRINDER TO REDUCE THE PARTICLE SIZE OF THE SOLIDS AND SIMULTANEOUSLY AGGLOMERATE THE PARTICLES OF GREATER HYDROPHOBICITY WHILE DISPERSING THE PARTICLES OF LESSER HYDROPHOBICITY AND SEPARATING THE AGGLOMERATES FROM THE RESULTANT DISPERSION. 